Arthrographic image quality and relative morbidity resulting from use of the nonionic dimer iotrolan and the ionic dimer ioxaglate sodium meglumine were compared in a prospective double-blind study performed in 80 patients. Radiographs obtained 2, 5, 10, 15, 20, and 25 minutes after injection of contrast agent were graded for diagnostic quality. Relative morbidity was evaluated by the physician during the examination and later by the patient by means of a questionnaire. Iotrolan demonstrated better image quality on serial radiographs in knee joints without previous effusions. Most differences were not significant. The mean duration of diagnostic-quality images for both contrast media was about 23 minutes. Iotrolan and ioxaglate caused equal postprocedural pain (in about 50% of patients). Other types of discomfort were less when iotrolan was used, but the differences were not significant. With regard to long-lasting image quality, both contrast media are suitable for arthrography.